1. Field of the Invention
This invention relates to a resin composition. More particularly, it relates to a resin composition which excels in formability including curing property and workability, produces a cured article excelling in stability at elevated temperatures and in mechanical strength, and when used as a matrix resin for a composite material, exhibits excellent adhesiveness with reinforcing fibers and a highly desirable fatigue-resistant characteristic.
2. Description of the Prior Art
As resins excelling stability at elevated temperatures, various heat-resistant resins represented by polyimide resin and polyamideimide resin may be mentioned. These heat-resistant resins, however, have serious drawbacks in formability as evinced by the fact that must be molded at a high temperature under a high pressure because of their high melting points, they must be cured at a high temperature under a high pressure for a long time, and they must be dissolved in special high-boiling solvents to be used efficiently. It is, therefore, extremely difficult to produce bulky shaped article or to produce article by continuously pultrusion molding or extrusion molding from these heat-resistant resins.
As resins excelling in formability including curing property and workability, such radical polymerization type resins as epoxy (meth)acrylates derived from such polyphenol type epoxy resins as bisphenol epoxy resins and novolac type epoxy resins and (meth)acrylic acids and unsaturated polyesters have been known. Generally, these resins are extensively used as vinyl ester resins or unsaturated polyester resins in a form incorporating therein such a radically polymerizing cross-linking agent as styrene. As resins excelling in adhesiveness with reinforcing fibers or in fatigue-resistant property, various epoxy resins of bis-phenol type and novolac type have been known.
These resins, however, are not necessarily duly satisfactory in terms of thermal stability at elevated temperatures. The insufficiency of thermal stability proves a serious hindrance to the development of applications. In the circumstances, an earnest desire has been expressed to develop a resin possessing notably improved thermal stability.
An object of this invention, therefore, is to provide a novel resin composition.
Another object of this invention is to provide a resin composition which excels in formability including curing property and workability, produces a cured article excelling both in stability at elevated temperatures and in mechanical strength, and, when used as a matrics resin for a composite material, exhibits excellent adhesiveness to reinforcing fibers and highly desirable fatigue-resistant property.